Shoe structure for centerless grinder



June 6; 1967 c. J. TERP ET AL 3,323,258

SHOE STRUCTURE FOR CENTERLESS GRINDER Filed Jan. 11, 1965 INVENTORS CHARLES J. TERR ARTHUR R. PETERSON "A T TORNEVS United States Patent O 3,323,258 SHOE STRUCTURE FOR CENTERLESS GRINDER Charles J. Terp and Arthur R. Peterson, Springfield, Vt., assiguors to Bryant Chucking Grinder Company, Springfield, Vt.

Filed Jan. 11, 1965, Ser. No. 424,496 1 Claim. (Cl. 51--103) ABSTRACT OF THE DISCLOSURE A low friction insert pad on the workpiece supporting shoe of a centerless grinding machine.

This invention relates to improvements in internal grinding machines of the type wherein an annular work piece is radially supported on a preformed outside surface for rotation in frictional relationship to supporting shoes peripherally spaced along the surface and a tool is applied to its inner periphery to generate an internal surface concentric to the preformed outer surface. An example of this type of grinding machine is disclosed in US. patent to Arms et al., No. 2,635,395, Apr. 21, 1953 and Terp No. 2,927,406, dated Mar. 8, l960. More particularly, this invention relates to an improved shoe assembly Work support which can be disassembled for convenient insertion and/or removal of the low-friction insert attached thereon.

In prior machines the supports are normally made of solid blocks of steel hardened or with carbide inserts brazed on to the blocks for Wear surfaces. This requires changing the whole block as they wear. This invention relates to a removable wear insert adapted to be detachably secured in an improved shoe assembly work support.

For a complete understanding of this invention, reference may be had to the following detailed description taken in connection with the accompanying drawings, wherein:

FIG. 1 is a side elevation illustrating a preferred embodiment;

FIG. 2 is a sectional view along line 2--2 of FIG. 1;

FIG. 3 is a side elevational View of the clip;

FIG. 4 is a side elevation illustrating a variation of the embodiment of FIG. 1; and

FIG. 5 is a representation of the shoe insert prior to assembly.

Referring to FIG. 1, 23 indicates a machine base attachment of the type illustrated in the patents cited hereinabove in the preferred embodiment, shoe assemblies 1 and 1 are detachably secured on the machine base 23 and in the plane of the feed movement. Since the shoe assemblies 1 and 1 are identical in construction it is to be understood that description of the elements of shoe assembly 1 also refers to the elements of shoe assembly 1. As shown in FIGS. 1 and 2, shoe assembly 1 has an enlarged portion 2 and a reduced end portion 3. The enlarged portion 2 has an adjustment slot 6 therethrough with a shoulder abutment 7 adapted to abut the underside of screwhead 8 of capscrew 9. The capscrew 9 is threadably received in tapped hole 11 of attachment 23. The adjustment slot 6 allows the shoe assembly 1 to be displaced along its principal axis in order to accommodate various diameters of workpieces 25. A shaft or spindle 27 is rotatably supported, not shown, and is adapted to be driven by conventional means, not shown. The rotatable tool spindle 2.7 supports grinding wheel 28 adapted to be placed in contact with a workpiece 25 in a manner and 3,323,253 Patented June 6, 1967 for the purpose well known in the art. The axis of spindle 27 is preferably located in a plane in proximity of the support determined axis of the workpiece; this plane being parallel to the feed movement, contains a line running through the center of spindle 27, defining a line of feed F, as shown in FIG. 1.

The shoe assembly 1 has a reduced end portion 3 with a shoulder recess 4 adapted to retainingly engage shoulder 14 of clip 13. Clip 13 has a clearance hole 15 therethrough for detachably securing said clip to the side of the reduced end portion 3 by means of machine screw 19. On the opposite elongated end of the clip 13, but extending generally parallel to shoulder 14 of clip 13 is a V-shaped recess 17, the purpose of which is to be disclosed herewith.

As shown in FIG. 1 and cross section of FIG. 2, the shoe insert 21 is detachably retained in arcuate recess 5 by two clips 13, one at each end of the shoe insert. The inserts, which are initially flat, are sprung into the arcuate recess 5 by tightening machine screws 19. The above mentioned V notches 17 retain the ends of the flat inserts 21 and force the insert to arch inwardly as the machine screws 19 are tightened. The tip portion 20 of the clip 13 is made low enough so as to be below the working surface of the shoe insert 21 of thickness T. The length L of the flat shoe insert 21 is precisely controlled, allowing the clips to be tightened down fully whole holding the shoe insert 21 in contact with the arcuate recess 5.

In the embodiment shown in the illustration, the sides of the shoe inserts 21 are further retained against sideways slippage by two arcuate shoulders 22. These are spaced apart by distance W, the width of the shoe insert 21.

It should be emphasized here that the contour radius of the reduced end portion 3, minus the insert thickness matches the accurate radius of the workpiece 25.

The shoes can be made of various plastics or metals as desired; the criterion being low wear, controlled friction, low compressibility and some flexibility.

The invention herein disclosed allows easy replacement of the wear surface inserts without removal of the entire shoe assembly.

In the preferred embodiment, the shoe assemblies 1 and 1 are shown degrees apart; however, this angle can be varied considerably as is well known practice. In the preferred embodiment, the shoe assembly 1 supports the workpiece 25 substantially in the line of feed F, while the shoe 1 is angled from it as describe-d.

Applicants have disclosed two illustrated embodiments of an improved radial work support for a grinding machine, FIG. 1 shows an internal grinder, FIG. 4 an external grinder. These illustrations are for the purpose of teaching one skilled in the art how to practice the invention and are limited only by the scope of the appended claim, wherein applicants are entitled to the full range of equivalents.

What is claimed is:

In an internal grinding machine having a base supporting a rotatable tool spindle, a tool adapted to be placed in working relationship with an internal surface of an annular workpiece, supports for the tool being arranged for relative transverse movement along a line of feed running through the axes of the workpiece and the tool spindle, improved means for radially supporting the perimeter of the workpiece for rotation about an axis, said improved means comprising: a support, a shoe assembly adjustably connected to said support, said shoe assembly including an arcuate recess adapted to radially support the perimeter of the workpiece, a low-friction shoe insert, said low-friction shoe insert adapted to be placed in radial contact between said workpiece and said arcuate recess, and means for detachably retaining said shoe insert, said means including a clip, said clip having a shoulder extending normal to the longitudinal axis of said clip, and a V- shaped recess at the end opposite to said shoulder normal to the longitudinal axis of said clip, said V-shaped recess including an abutting surface adapted to engage the end of said shoe insert to prevent withdrawal thereof.

References Cited UNITED STATES PATENTS Fors 51238 Heim 51-103 X Arms et al 51103 Cann et a1. 51-103 Terp 51103 Humes et a1. 51103 10 LESTER M. SWINGLE, Primary Examiner. 

